High energy impact-based material removal apparatus

ABSTRACT

A material removal apparatus for removing a material from a surface is provided. The material removal apparatus comprises a frame having distal and proximal frame portions, the proximal frame portion comprising a handle. A tool shaft is slidably mounted to the frame, the tool shaft having proximal and distal shaft ends and a longitudinal shaft axis. The tool shaft is movable between a first shaft position and a second shaft position distal to the first position. A tool head attached to the distal shaft end is adapted for engaging the material to be removed. The material removal apparatus also comprises an impulse delivery arrangement attached to the frame. The impulse delivery arrangement is adapted for selectively applying a discrete impulsive force to the proximal shaft end.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part of U.S. application Ser. No.10/972,283 filed Oct. 25, 2004, which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

The invention relates to the field of construction equipment, and inparticular relates to powered tools for removing materials such asshingles or fasteners from surfaces, and for demolition.

Shingles are frequently used to protect inclined roofs. The shingles maybe asphalt, or wood, or tiles, and may be attached to the roof by nailsor staples. Asphalt shingles faced with granular stone are often nailedinto overlapping rows, with the upper row overlapping the lower row inorder to keep out water. A layer of tar paper may be underneath theshingles. The shingles and tar paper are often attached to a wood roof.The wood roof often comprises inclined plywood nailed onto rafters.

Shingles degrade with time and weather, and must be replaced regularly.Old shingles and tar paper may be removed using many types of manualtools such as: crowbar, hammer, shovel, and pitchfork. Many nails areleft behind after the shingles are removed with these manual tools. Anyremaining nails must be removed after the shingles are removed. Thus,removing shingles is very labor intensive, very expensive, and veryslow.

Numerous attempts have been made to improve the removal of shingles,felt, and nails from roof surfaces. For example, U.S. Pat. No. 4,663,995discloses a machine with a powered lifting plate to lift the nails out.This machine requires the human operator to physically push the machineinto position before activating the powered lifting plate. U.S. Pat. No.4,709,479 discloses a powered lifting plate to lift the felt and nailsout, and also powered wheels to simultaneously push the machine forward.U.S. Pat. Nos. 4,763,547 and 4,858,503 and 5,001,946 disclose variouspowered lifting plates.

Another approach to the problem is to use a reciprocating tool to stripmaterials from the roof surface. U.S. Pat. Nos. 5,076,119; 5,71,047;5,741,047; and 6,393,948 each disclose a reciprocating blade. U.S. Pat.No. 5,800,021 also discloses a reciprocating blade, this time with theblade comprising wedge-shaped teeth. U.S. Pat. No. 5,906,145 disclosesthe use of a vibrating shovel blade.

None of the above solutions have proven to be completely satisfactory.Most of the tools that have been used until now have been bulky anddifficult to manipulate. Many of them are usable only to remove theshingles themselves without regard to the nails holding them to thesurface. In general, vibratory or reciprocating tools are relativelyineffective for removing shingles and fasteners from roofing surfaces.

SUMMARY OF THE INVENTION

An illustrative embodiment of the invention provides a material removalapparatus for removing a material from a surface. The material removalapparatus comprises a frame having distal and proximal frame portions,the proximal frame portion comprising a handle. A tool shaft is slidablymounted to the frame, the tool shaft having proximal and distal shaftends and a longitudinal shaft axis. The tool shaft is movable between afirst shaft position and a second shaft position distal to the firstposition. A tool head attached to the distal shaft end is adapted forengaging the material to be removed. The material removal apparatus alsocomprises an impulse delivery arrangement attached to the frame. Theimpulse delivery arrangement is adapted for selectively applying adiscrete impulsive force to the proximal shaft end.

Another illustrative embodiment of the invention provides anothermaterial removal apparatus for removing a material from a surface. Thematerial removal apparatus comprises a frame having distal and proximalframe portions, the proximal frame portion comprising a handle. Thematerial removal apparatus also comprises an impulse deliveryarrangement attached to the frame. The impulse delivery arrangementcomprises an air cylinder having proximal and distal cylinder endsintersected by a longitudinal cylinder axis and being connectable to apressurized air source. A piston is slidably disposed within the aircylinder so as to be movable along the longitudinal cylinder centerlinebetween a first piston position to a second piston position distal tothe first position. The piston and the air cylinder are configured sothat movement of the piston may be controlled through selectiveintroduction of compressed air from the pressurized air source into theair cylinder. The material removal apparatus further comprises a toolshaft slidably mounted to the frame. The tool shaft has proximal anddistal shaft ends and a longitudinal shaft axis that is substantiallycollinear with the longitudinal cylinder axis. The tool shaft is movablebetween a first shaft position and a second shaft position distal to thefirst position. The first shaft position is established so that thepiston can make contact with the proximal end of the tool shaft when thetool shaft is in the first position and the piston is in a contactposition intermediate the first and second piston positions. A tool headattached to the distal end of the tool shaft is adapted for engaging thematerial to be removed.

Further objects, features and advantages of the invention will beapparent from the detailed description below taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphic comparison of the force applied by material removaldevices according to the invention with the force applied by aconventional air hammer;

FIG. 2 is a side view of a material removal apparatus according to anembodiment of the invention;

FIG. 3 is a top view of the apparatus of FIG. 2;

FIG. 4 is a section view of a portion of a material removal apparatusaccording to an embodiment of the invention;

FIG. 5 is a perspective view of a tool head that may be used inconjunction with material removal apparatus according to an embodimentof the invention;

FIG. 6A is a perspective view of a tool head that may be used inconjunction with material removal apparatus according to an embodimentof the invention;

FIG. 6B is a section view of the tool head of FIG. 6A;

FIG. 7 is a perspective view of a tool head that may be used inconjunction with material removal apparatus according to an embodimentof the invention;

FIG. 8A is a side view of a tool head that may be used in conjunctionwith material removal apparatus according to an embodiment of theinvention;

FIG. 8B is a top view of the tool head of FIG. 8A;

FIG. 9 is a top view of a material removal apparatus according to anembodiment of the invention; and

FIG. 10 is a section view of a portion of a material removal apparatusaccording to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a relatively lightweight, poweredmaterial removal apparatus that can be used to remove materials such asshingles and nails from inclined roofs, and for other removal anddemolition tasks. The material removal apparatus uses an impactor todeliver discrete high impact pulses to a tool for removing materialsfrom a surface. The use of a compressed air driven piston as theimpactor allows the delivery of high kinetic energy and momentum to atool shaft and tool head through an impulsive impact. The kinetic energyand momentum from the tool shaft is then transmitted to the material tobe removed in a single high energy stroke rather than multiple lowerenergy pulses delivered through a generally vibrating or reciprocatingmotion. The discrete high energy stroke of the removal tool of theinvention serves to force the tool head beneath the materials to beremoved. The tool head may be configured so that it may be subsequentlyoperated as a lever to lift the material from the surface.

As discussed above, existing tools often use reciprocating action formaterial removal. FIG. 1 illustrates the conceptual difference betweenthe material removal apparatus of the invention and a reciprocating toolsuch as an air hammer. The material removal apparatus of the inventionapplies a single, discrete high energy impulsive force that may be twoorders of magnitude higher than the repetitive force applied by an airhammer of similar size. This single, high energy pulse has been found tobe more effective for many material removal applications and, inpneumatic embodiments, uses significantly less air than an air hammer.

The main components of a material removal apparatus according to theinvention will now be described. The tool head is attached to the distalend of a tool shaft slidably mounted to a housing or frame. The toolhead and tool shaft may be separate parts joined or removably attachedto one another or may be formed as a single integral part. The proximalend of the tool shaft (i.e., the end nearer the user of the materialremoval apparatus) is adapted for receiving an impulse load from apiston or other actuator body. The frame or housing supports an impulsedelivery arrangement that is adapted for delivering a discrete impulseload to the proximal end of the tool shaft upon demand. This load istransmitted to the tool head, which is propelled distally along its axisuntil it reaches a maximum stroke length or until it encounters anobstruction. The energy imparted to the tool head is transmitted to anymaterials or objects encountered by the tool head during its stroke.

The material removal apparatus may have a stiff, light-weight frame towhich various components may be mounted. The frame may also form anintegral portion of various components, such as the exterior wall of anair cylinder, or the exterior wall of an air accumulator. In someembodiments, the frame may be replaced or supplemented by a housing thatserves to protect the working components from the environment, and toprotect the user from injury caused by moving parts. The housing mayalso serve as a portion of the working components. For example, thehousing may serve as the exterior wall of an air cylinder.

After the tool head is impulsively driven under or into the material tobe removed, the frame and the tool head may be used together much like aconventional handle or pry bar for lifting up the material. The framemay have a handle of any suitable shape, e.g. a D-shaped or T-shapedhandle, and may have an additional side mounted tubular handle forguiding and controlling the material removal apparatus manually.

In some embodiments of the invention, the impulse delivery arrangementincludes a compressed air-driven actuator comprising a piston slidablydisposed in an air cylinder. Compressed air may be selectivelyintroduced into the air cylinder through the use of a multi-port valve.The air cylinder and piston are arranged and mounted so that the pistontravels along a path axially aligned with the axis of the tool shaft.The piston and cylinder are constructed so that a distal portion of thepiston makes contact with the proximal end of the tool shaft when thepiston is at or near the distal end of its stroke. The compressedair-driven actuator may be a single-acting or double-acting actuator.

Mounting points may be provided on the frame for mounting the aircylinder and valve, a trigger for selectively activating the valve, andassociated tubing. Guides incorporated into the frame may be used toaxially align the tool shaft with respect to the air cylinder. Thehandle may have a trigger mechanism that operates the multi-port valveused to control the airflow to the air cylinder. The frame may havestops for limiting the travel of the tool shaft.

Compressed air imparts great kinetic energy and momentum to the piston.Near the end of its stroke, the piston provides a hammering impulsivestrike to a tool assembly. The hammering impulsive strike of the pistonagainst the tool assembly transfers much or all of this kinetic energyand momentum to the tool assembly. The tool assembly then transmits thehammering impulsive strike to or under the material to be removed,similarly transferring much or all of the kinetic energy and momentum tothat material.

As noted above, the tool assembly may comprise a tool shaft and a toolhead. The tool shaft may be slidably mounted to the frame or housingusing guides that provide axial alignment with the piston shaft, andthat allow movement in the axial direction. The tool shaft may have anon-circular (e.g., elliptical or square or other polygonal shape) crosssection with the guides shaped in complementary fashion so as torestrict rotational movement. This assures that the rotational angle ofthe tool head may be fixed relative the frame. The tool shaft may extendfrom the lower guide of the frame.

In some embodiments, the tool head may be removably attached to the toolshaft by means of pinning or other fastening method. This allows foreasy replacement of the tool head. Alternatively, the tool head may bepermanently attached to the tool shaft or integrally formed therewith.The tool head may be configured in any of a variety of forms tailored toparticular uses. These may include, without limitation, the end of aconventional roofing shovel, a nail removal shovel blade with integralfulcrum, flat bars, scrapers, wedges, punches, cutting blades, andspecialty application tools such as guided prying wedges or cuttingtools (e.g. a wedge with a channel shaped guide attached to the bottomof the wedge to guide it along the top of a rafter when removingsheathing).

In a particular embodiment, the tool head includes a mounting tubeadapted for receiving the distal end of the tool shaft. The mountingtube may be fixed to the tool shaft using any suitable bonding materialor fastening mechanism. The distal-most shaft guide may be configuredwith a larger diameter than the more proximal guide(s) in order toaccommodate the mounting tube. The inserting of the tool shaft into thetool mounting tube effectively increases the moment of inertia of thecombined members to resist bending.

In alternative embodiments, the impulse delivery arrangement of thematerial removal apparatus may use an impactor driven by sources ofenergy other than compressed air. These may include, for example,pressurized liquids (hydraulics), chemical reactions, or electricity, orother sources of energy. Chemical reactions may include, withoutlimitation: solid explosive charges similar to those used in some nailguns, liquid explosive charges (e.g., a fuel/air mixture). Electricalmay include using a battery to provide electricity. A a small gasolineburning piston engine may be used provide mechanical power.

Many sources of energy may provide energy at relatively low levels ofpower, and in these circumstances the impulse delivery arrangement mayaccumulate the energy before delivering the energy in an impulse. Forexample, a small light electric motor may slowly compress a powerfulspring.

In some embodiments, the material removal apparatus may include apressurizable air accumulator, which may be discharged upon triggeringthe valve. This may reduce the pressure drop in the compressed air linewhen the piston is triggered. The air accumulator may be a separatevessel attached to the frame or may be incorporated into the handle. Thehandle may also serve as a manifold, routing air to and from the piston.In underwater use, the exhausted air may be routed to the surface. Alsoin underwater use, both sides of a double action piston may be at leastslightly pressurized in order to prevent water intrusion (i.e., operateunder positive pressure with respect to the external water pressure).

A single acting piston reduces the number of exposed hoses, does notneed a pressure regulator, and is very reliable. The single actionpiston, however, requires a restoring force to return it to its initialposition after delivering an impulse to the tool shaft. The restoringforce may be in the form of a spring, which serves to bias the piston inits ready position adjacent the proximal end of the air cylinder. Adouble acting piston requires no return spring pressure to overcome andmay be shorter and lighter in weight. The exhaust return pressure can becontrolled by a pressure regulator which may reduce the impact of pistonreturn, and can be used underwater.

It will be understood that the bulk of the material removal apparatusweight may be found near the upper end of the material removal apparatusto provide the operator with better control and ease of handling theapparatus.

Operation of exemplary embodiments of the present invention will now bedescribed. Any specific dimensions, angular orientations orconfigurations depicted in the figures are for representation of theexemplary embodiments herein and should not be interpreted as limitingor restrictive to the scope of the invention.

With reference to FIGS. 2-4, a material removal apparatus 100 accordingto an exemplary embodiment of the invention comprises a frame 3, animpulse delivery arrangement 43, and a tool assembly 44. The frame 3 isstructured to support the impulse delivery arrangement 43 and the toolassembly 44. The frame 3 may be formed from any type of lightweightstructural members. In a preferred embodiment, the frame is formed fromone or more tubular members to which the other components of thematerial removal apparatus may be attached. In the illustratedembodiment, the frame 3 is formed as a single elongate tubular memberhaving a distal portion to which the tool assembly 44 is attached, anintermediate portion to which the impulse delivery arrangement 43 isattached and a proximal portion 40 that forms a handle for the user. Theintermediate portion of the frame 3 may have a curve 19 that serves toalign the impulse delivery arrangement 43 with the tool assembly 44.

The tool assembly 44 comprises a tool head 15 removably attached to thedistal end of a tool shaft 9. The tool shaft 9 is an elongate memberthat is strong enough to receive an impulse load and transmit it to thetool head 15 without bending and with minimal energy loss. The toolshaft 9 may have a substantially square cross-section. The tool head 15includes a mounting tube 12 adapted for receiving the distal end of thetool shaft 9. The mounting tube 12 is held in place on the end of thetool shaft 9 by pins 11 or other removable fasteners. As will bediscussed in more detail below, the tool head 15 may be configured in avariety of shapes to facilitate material removal.

The tool assembly 44 is held to the frame 3 by a plurality of guidesthrough which the tool shaft 9, the mounting tube 12 or both the toolshaft 9 and the mounting tube 12 are slidably disposed. In theillustrated embodiment, an upper portion of the tool shaft 9 is disposedthrough a proximal guide 10 and the mounting tube 12 is disposed througha distal shaft guide 16. The shaft guides 10, 16 are configured toconform to and slidably accommodate the tool shaft 9 and mounting tube12 with minimal friction and minimal play.

The impulse delivery arrangement 43 of the material removal apparatus100 includes an air cylinder 6 a multi-port valve 4, and a triggermechanism 2. The air cylinder 6 is an annular tube sealed at itsproximal end by a top cap 17 and at its distal end by a bottom cap 18.The top cap 17 has a threaded port 20 adapted for receiving fittingsattached to the air supply tubing 5. O-rings 21 serve to seal the cap17. The air cylinder 6 may also include a bottom cap 18 that may containholes 24 to let air in or out and a shaft guide 25 to seal around andguide a piston shaft 8. Additional O-rings 21 serve to seal the bottomcap 18.

A piston 52 may have a piston head 23 with a piston shaft 8 extendingdistally therefrom. The piston head 23 is adapted for slidabledisposition within the interior of the air cylinder 6 and for sealingthe portion of the air cylinder interior proximal to the piston head 52.Piston rings 22 may be used to maintain the seal. The piston head 23 isattached to the proximal end of the piston shaft 8 which is slidablydisposed through the shaft guide 25 so that the piston shaft 8 extendsdistally from the distal end of the air cylinder 6.

The air cylinder 6 and piston 52 are configured and positioned so thatthe piston shaft 8 is axially aligned with the tool shaft 9. When thepiston head 23 is in the initial or ready position shown in FIG. 2,there is a gap between the distal end of the piston shaft 8 and theproximal end of the tool shaft 9. When compressed air is introducedthrough the port 20, the piston 52 is forced to move rapidly in thedistal direction relative to the air cylinder 6. This causes the distalend of the piston shaft 8 to make contact with the proximal end of thetool shaft 9 and transmit an impulse load thereto.

The air cylinder 6 is attached to the frame 3 using a plurality ofbrackets or other suitable mounting hardware. A proximal mount 13 may beused to mount the top cap 17 to the frame 3 and a distal mount 14 may beused to mount the bottom cap 18.

The multi-port valve 4 of the impulse delivery arrangement 43 may be anysuitable valve assembly that provides rapid cycling for delivery of airfrom a compressed air source to the air cylinder 6 through tubing 5. Themulti-port valve 4 may be electrically controlled by a trigger 2 mountedto the handle 40 or elsewhere on the frame 3. Air may be delivered tothe valve 4 using any suitable tubing. Alternatively, the handle portion40 of the frame 3 may be configured as an air reservoir having an airinlet 1 and an outlet to which the valve 4 is in fluid communication.

As discussed above, the frame 3 may be configured for use as a lever topry up material. To facilitate this action, the material removalapparatus 100 may include a fulcrum or engagement fixture 26 attached tothe distal end of the frame. The engagement fixture 26 may be removablyattached to the frame 3 with a fulcrum pin 27 or other removablefastener. Alternatively, the engagement fixture may be permanentlyattached to the frame 3 or may be integrally formed therewith.

The handle portion 40 of the frame 3 may be formed in a “D” or “T”shape. The handle portion 40 may be attached to the other portions ofthe frame 3 or may be integrally formed therewith.

As discussed above, the tool head may be formed in any of a variety ofconfigurations. FIGS. 5-8 are exemplary embodiments of variousconfigurations for the tool head 15. FIG. 5 illustrates a crowbar-shapedtool head 15 a that is useful for removing single large nails, and forremoving boards. FIGS. 6A and 6B illustrate a chisel-shaped tool head 15b that is useful for breaking fasteners such as small bolts. In thisconfiguration, a channel 90 is formed at the bottom of the tool head 15b for guiding the tool along a rafter while removing sheathing, orguiding along a stud while removing drywall. FIG. 7 illustrates ascraper-shaped tool head 15 c that is useful for removing adhesivelyattached tiles and tar paper and for scraping ship hull surfaces. FIG. 8illustrates a pointed shovel shaped tool head 15 d. This tool head 15 dhas a flat horizontal component 92 to penetrate under shingles and avertical component 94 to act as a wedge to raise the shingles.

In an alternative embodiment of the invention, a material removalapparatus uses an impulse delivery arrangement with a compressed airdriven impactor that is particularly well suited to underwater use. Withreference to FIGS. 9 and 10, a material removal apparatus 200 accordingto this embodiment includes a frame 203, an impulse delivery arrangement243, a tool assembly 244 and a housing 233. As shown in FIG. 9, theframe 203 comprises an air accumulator 232 that may be integrated intothe handle portion 202 of the frame 203. For example, the airaccumulator 232 may be a hollow portion of the frame 203 that defines achamber 234 that is sealed to provide a pressurized reservoir forcompressed air introduced through the air inlet 201.

The chamber 234 of the air accumulator 232 is connected by tubing 205 toa multi-port valve 204 and by separate tubing 207 to a pilot valve 231.The multi-port valve 204 is connected to an air cylinder 206 by an inlettube 251 and an outlet tube 253. The multi-port valve 204 is alsoconnected to an exhaust tube 261, the opposite end of which is open tothe atmosphere.

The air cylinder 206 is an annular cylinder that is open at its distalend and closed by a cylinder cap 255 at its proximal end. The inlet tube251 is connected by a fitting to the cylinder cap 255 so that air can bepassed into the air cylinder through a cylinder inlet port 257. Theoutlet tube 253 is connected to the air cylinder 206 near its distal endso that air can be passed out of the air cylinder 206 through thecylinder outlet port 259. A proximal portion of a cylindrical shafthousing 233 is fixedly disposed within the distal end of the aircylinder 206. The cylindrical housing is also attached to the frame 203.

A piston 223 is slidably disposed within the interior of the aircylinder 206 so that when compressed air is introduced through the inletport 257 and/or removed through the outlet port 259 so as to produce apressure differential across the piston 223, the piston 223 is forced tomove in the distal direction. Conversely, if air is introduced into thecylinder through the outlet port 259 and/or withdrawn from the inletport 257, the piston 223 is forced to move in the proximal direction.The piston 223 may be provided with seals 242 to prevent the flow of airaround the piston 223.

The multi-port valve 204 is configured to control the flow of air intoand out of the air cylinder 206 through the inlet and outlet ports 257,259. The multi-port valve 204 may be adapted to control the air flow sothat, for an impulse stroke, a large pressure differential isestablished across the piston 223 so as to produce a large accelerationof the piston 223 in the distal direction. The multi-port valve 204 mayalso be adapted to control the air flow so that, for a return stroke, asmaller pressure differential is established across the piston 223 so asto produce a smaller acceleration of the piston 223 in the proximaldirection. A pressure regulator (not shown) may be used to limit thepressure differential on the proximal return stroke.

The outlet tube 253 may be a separate tube as shown in FIG. 9 or,alternatively, may be integrally formed with or bored into the wall ofthe air cylinder 206. The air cylinder 206 may also serve as a loadbearing portion of the frame 203. In other embodiments, the air cylinder206 and outlet tube 253 may be disposed within an outer housing that maybe attached to or included as a load-bearing part of the frame 203.

The tool assembly 244 includes a tool shaft 209 and a tool head 215. Thetool head 215 may be substantially similar to those of earlier describedembodiments. The tool shaft 209 is configured and positioned so that itsproximal end 260 is disposed within the interior of the air cylinder 206with its longitudinal axis aligned with the air cylinder centerline 258.The tool shaft 209 may have a broadened contact head 262 at its proximalend 260 to increase the contact area between the piston 223 and the toolshaft 209 during an impulse stroke. The tool shaft 209 may have a singlecross-sectional shape that may be circular, elliptical, square or othergeometric shape. In some embodiments, the tool shaft 209 may have aplurality of shapes. In the embodiment illustrated in FIG. 10, the toolshaft 209 has a proximal portion 290 with a circular cross-section and adistal portion 292 with a non-circular cross-section.

The tool shaft 209 is slidably supported and aligned by a plurality ofbushings sized and shaped to conform to the cross-section of the toolshaft 209. An air cylinder bushing 270 is disposed within the interiorof the air cylinder 206 distal to the outlet port 259. The air cylinderbushing 270 is held in place by a bushing retainer 271, which, incombination with a seal 272, serves to seal the distal end of the aircylinder 206. The use of a circular shaft cross-section and a circularair cylinder bushing 270 allows the tool shaft 209 to be selectivelyrotated relative to the air cylinder 206.

One or more additional bushings may be disposed within the shaft housing233. In a particular embodiment, there is a proximal shaft housingbushing 273 and a distal shaft housing bushing 276 fixedly attached tothe interior wall of the housing 233. The proximal shaft housing bushing273 is held in place by a bushing retainer 274. An optional seal 275 maybe provided, which together with the bushing retainer 274 seals theproximal end of the shaft housing 233. The distal shaft housing bushing276 is held in place by a bushing retainer 277 and is configured toconform to the non-circular shaft portion 292. As a result, the toolshaft 209 cannot be rotated relative to the shaft housing 233. The shafthousing 233, however, may be mounted so that it can be rotated relativeto the air cylinder 206. By virtue of the non-circular portion 292 ofthe tool shaft 209, rotation of the shaft housing 233 relative to theair cylinder 206 will also rotate the tool shaft 209 relative to the aircylinder 206. This allows for easy adjustment of the rotational angle ofthe tool head 215 while maintaining an air-tight and water-tight seal ofthe air cylinder 206.

The material removal apparatus 200 may be activated through the use of acontrol lever 229, which activates the pilot valve 231. The pilot valve231 introduces air into the multi-port valve 204 for actuation thereof.Upon activation, the multi-port valve 204 establishes a pressuredifferential around the piston 223 causing it to accelerate and strikethe contact head 262 of the tool shaft 209 with an impulse load. Thetool shaft 209 transmits this load to the tool head 215 which impartsthe impulse to the material to be removed. Upon release of the controllever 229, the multi-port valve 204 establishes a return differentialpressure around the piston 223 to cause the piston 223 to return to theproximal end of the air cylinder 206.

The tool shaft 209 may be returned to its proximal position by theaction of the user in moving the entire material removal apparatus 200in the distal direction. If and when the tool head 215 encountersresistance to the distal movement (e.g., friction or an obstruction),continued movement of the tool frame 203 in the distal direction causesthe tool head 215 and tool shaft 209 to move proximally relative to thetool frame 203 and the impulse delivery arrangement 243 until the toolshaft is in its proximal position or until an additional impulse isapplied.

In some embodiments, an automatic trigger arrangement may be used totrigger additional impulse applications whenever the tool shaft isreturned to its proximal position as a result of encountering resistanceto distal movement of the tool head 215. The trigger arrangement mayinclude any switch mechanism (e.g., a micro-switch) that closes totrigger the pilot valve 231 when the tool shaft 209 is in apredetermined position relative to the frame 203 and/or the impulsedelivery arrangement 243. When the impulse is applied, the shaft 209 ismoved distally away from this predetermined position and the switchopens. In some such embodiments, a biasing mechanism such as a springmay be used to bias the tool shaft 209 away from the predeterminedproximal position so that the automatic trigger mechanism will only betriggered upon the tool head 215 encountering a predetermined level ofresistance.

In alternative embodiments to the above, a biasing mechanism may be usedto bias the tool shaft 209 in the proximal direction. This may serve toreturn the tool shaft more quickly to its proximal position for repeatedimpulse application.

Because of its sealed impulse delivery arrangement, the material removalapparatus 200 is particularly adapted for use in an underwaterenvironment. In addition, its double action air cylinder provides forrapid reset of the device for application of sequential discrete pulsesto the material to be removed.

EXAMPLES

It will be understood that the material removal apparatus of the presentinvention may be constructed and scaled to any size for a particularapplication. In a typical hand-held, one-man material removal apparatusaccording to the invention, the combined weight of the tool shaft andtool head is in a range of about 1 pound and to about 5 pounds. Atypical impactor weight is also in a range of about 1 pound and to about5 pounds. In embodiments in which the impactor is a compressedair-driven piston, the operating air pressure may be in a range of about30 psi to about 175 psi. The piston diameter is typically from about 1to about 3 inches and the piston stroke is typically in a range fromabout 3 inches to about 9 inches.

An exemplary embodiment of a compressed air-driven material removalapparatus according to the invention may be used to illustrate theenergy imparted to the tool head. The exemplary material removalapparatus has a piston with a diameter of 3.0 inches and a piston strokeof 2.0 inches. The weight of the piston is 2 pounds, and the combinedweight of the tool shaft and tool head is 2 pounds. The area of the topof the piston is equal to 3.14 times the square of the piston radius,which equals 7.06 square inches. The force acting on the piston equalsthe cross-sectional area of the piston times the differential pressureacross the piston. For a differential pressure of 100 psi, the force onthe piston is 706 lbf. As the piston is accelerated distally, it willhave a kinetic energy level equal to the work done in displacing it fromits initial position; i.e., K.E.=Work=Force*Distance. Assuming an idealone dimensional elastic collision between the piston and the tool shaft,the maximum energy that could be imparted to the tool shaft (“maximumimpact energy”) can be calculated. The maximum impact energy will beachieved if the collision occurs at the end of the full stroke length ofthe piston. For a force of 706 lbf and a stroke of 2.0 inches, themaximum impact energy is 118 ft-lbf.

A range of the maximum impact energy for a hand-held removal tool can beestablished using the parameter ranges noted above. At one end of therange, a material removal apparatus has a piston diameter of 1.0 inch, apiston stroke of 3 inches, a piston weight of 1 pound and a toolshaft/head weight of 1 pound. For an air pressure differential of 30psi, the maximum impact energy is 5.9 ft-lbf. At the other end of therange, a material removal apparatus has a piston diameter of 3.0 inches,a piston stroke of 9 inches, a piston weight of 5 pounds and a toolshaft/head weight of 5 pounds. For an air pressure differential of 175psi, the maximum impact energy is 927 ft-lbf.

It can therefore be seen that a one man material removal apparatus ofthe compressed air/piston type can achieve a maximum impact energy in arange of about 5 ft-lbf to about 1000 ft-lbf.

It will be readily understood by those persons skilled in the art thatthe present invention is susceptible to broad utility and application.Many embodiments and adaptations of the present invention other thanthose herein described, as well as many variations, modifications andequivalent arrangements, will be apparent from or reasonably suggestedby the present invention and foregoing description thereof, withoutdeparting from the substance or scope of the invention.

While the foregoing illustrates and describes exemplary embodiments ofthis invention, it is to be understood that the invention is not limitedto the construction disclosed herein. The invention can be embodied inother specific forms without departing from the spirit or essentialattributes.

1. A material removal apparatus for removing a material from a surface,the material removal apparatus comprising: a frame having distal andproximal frame portions, the proximal frame portion comprising a handle;a tool shaft slidably mounted to the frame, the tool shaft havingproximal and distal shaft ends and a longitudinal shaft axis, the toolshaft being movable between a first shaft position and a second shaftposition distal to the first position; a tool head attached to thedistal shaft end, the tool head being adapted for engaging the materialto be removed; and an impulse delivery arrangement attached to theframe, the impulse delivery arrangement being adapted for selectivelyapplying a discrete impulsive force to the proximal shaft end.
 2. Amaterial removal apparatus according to claim 1 wherein the impulsedelivery arrangement comprises an impactor adapted for selectivelycontacting the proximal shaft end to apply the discrete impulsive forcethereto and means for accelerating the impactor to a desired impactvelocity with which the impactor contacts the proximal shaft head.
 3. Amaterial removal apparatus according to claim 2 wherein the impactor hasa kinetic energy in a range of about 5 ft-lbf to about 1000 ft-lbf atthe impact velocity.
 4. A material removal apparatus according to claim1 wherein the apparatus is sized for carriage and use by a single humanuser.
 5. A material removal apparatus according to claim 1 furthercomprising means for biasing the tool shaft toward the first shaftposition.
 6. A material removal apparatus according to claim 1 whereinthe impulse delivery arrangement comprises: an air cylinder having aclosed proximal cylinder end and a distal cylinder end intersected by alongitudinal cylinder axis, the air cylinder being connectable to apressurized air source for fluid communication therewith; a pistonslidably disposed within the air cylinder so as to be movable along thelongitudinal cylinder centerline between a first piston position and asecond piston position distal to the first position, wherein the pistonand the air cylinder are configured so that movement of the piston maybe controlled through selective introduction of compressed air into theair cylinder and wherein the longitudinal shaft axis is substantiallycollinear with the longitudinal cylinder axis and the first shaftposition is established so that the piston can make contact with theproximal end of the tool shaft when the tool shaft is in the firstposition and the piston is in a position intermediate the first andsecond piston positions.
 7. A material removal apparatus according toclaim 6 wherein the air cylinder has an inner cylindrical wall and thedistal cylinder end is open and wherein the tool shaft is mounted to theframe by an annular cylindrical housing having proximal and distalhousing ends, the proximal end being disposed within the air cylinderand being attached to the inner cylindrical wall so as to extenddistally from the distal cylinder end.
 8. A material removal apparatusaccording to claim 7 wherein a first portion of the tool shaft isslidably disposed through a first bushing mounted to the innercylindrical wall proximal to the cylindrical housing and wherein asecond portion of the tool shaft is slidably disposed through a secondbushing mounted within the cylindrical housing
 9. A material removalapparatus according to claim 7 wherein the first portion of the toolshaft has a circular cross-section and the second portion of the toolshaft has a non-circular cross-section.
 10. A material removal apparatusaccording to claim 7 further comprising a seal mounted to the firstbushing, the seal being adapted to inhibit fluid leakage into or out ofa portion of the air cylinder proximal to the first bushing.
 11. Amaterial removal apparatus according to claim 3 further comprising acontrol valve adapted for selectively controlling a flow of compressedair from the compressed air source to the air cylinder.
 12. A materialremoval apparatus according to claim 3 further comprising an airreservoir in selective fluid communication with the air cylinder andbeing connectable to the compressed air source.
 13. A material removalapparatus according to claim 12 wherein the air reservoir is integrallyformed with the frame.
 14. A material removal apparatus for removing amaterial from a surface, the material removal apparatus comprising: aframe having distal and proximal frame portions, the proximal frameportion comprising a handle; a tool shaft slidably mounted to the frame,the tool shaft having proximal and distal shaft ends and a longitudinalshaft axis, the tool shaft being movable between a first shaft positionand a second shaft position distal to the first position; a tool headattached to the distal shaft end, the tool head being adapted forengaging the material to be removed; impact means for selectivelytransferring an impact energy to the proximal shaft head; and means foraccelerating the impact means to a desired impact velocity.
 15. Amaterial removal apparatus according to claim 14 wherein the impactmeans comprises a piston.
 16. A material removal apparatus according toclaim 15 wherein the means for accelerating comprises an air cylinderselectively connectable to a compressed air source, the piston beingslidably disposed in the air cylinder for acceleration by saidcompressed air.
 17. A material removal apparatus according to claim 14wherein the impact energy is in a range of about 5 ft-lbf to about 1000ft-lbf.
 18. A material removal apparatus according to claim 14 whereinthe apparatus is sized for carriage and use by a single human user. 19.A material removal apparatus for removing a material from a surface, thematerial removal apparatus comprising: a frame having distal andproximal frame portions, the proximal frame portion comprising a handle;an impulse delivery arrangement attached to the frame, the impulsedelivery arrangement comprising an air cylinder having proximal anddistal cylinder ends intersected by a longitudinal cylinder axis andbeing connectable to a pressurized air source, and a piston slidablydisposed within the air cylinder so as to be movable along thelongitudinal cylinder centerline between a first piston position to asecond piston position distal to the first position, the piston and theair cylinder being configured so that movement of the piston may becontrolled through selective introduction of compressed air into the aircylinder; a tool shaft slidably mounted to the frame, the tool shafthaving proximal and distal shaft ends and a longitudinal shaft axis thatis substantially collinear with the longitudinal cylinder axis, the toolshaft being movable between a first shaft position and a second shaftposition distal to the first position, wherein the first shaft positionis established so that the piston can make contact with the proximal endof the tool shaft when the tool shaft is in the first position and thepiston is in a contact position intermediate the first and second pistonpositions; and a tool head attached to the distal end of the tool shaft,the tool head being adapted for engaging the material to be removed. 20.A material removal apparatus according to claim 19 wherein the aircylinder has an inner cylindrical wall and the distal cylinder end isopen and wherein the tool shaft is mounted to the frame by a an annularcylindrical housing having proximal and distal housing ends, theproximal end being disposed within the air cylinder and being attachedto the inner cylindrical wall so as to extend distally from the distalcylinder end.
 21. A material removal apparatus according to claim 19wherein the piston has a kinetic energy in a range of about 5 ft-lbf toabout 1000 ft-lbf when the piston is in the contact position.